In this work we discuss the possibility that the observed effect is a signal from dark matter in the
hidden sector. While there are models in the literature where the hidden sector is used for the
explanation of the Xenon-1T excess, our analysis differs from them in several ways. In our analysis
we use the Stueckelberg extension of
the Standard Model where the Stueckelberg sector consists of an additional \(U(1)\)  gauge boson interacting via kinetic mixing with the visible sector.
In many previous works a single Dirac fermion is used which is then
split into two Majoranas which are given different masses [1]}, [2]}.
In our analysis we consider two Dirac fermions in the hidden sector carrying \(U(1)\)  charges with a small mass splitting and interacting
with the dark photon generated by the Stueckelberg
mechanism. In the analysis, both the freeze-in and freeze-out mechanisms operate to
generate the desired relic density. The analysis given here satisfies all the relevant constraints
on kinetic mixing between the hidden sector and the visible sector
and on the dark photon mass from the
CRESST 2019 DM-nucleon scattering cross section, from the neutrino experiment CHARM [3]} whose results are reinterpreted as limits on the dark photon [4]}
as well as from the Planck relic density experiment.
The outline of the rest of the paper is as follows: In section 
we discuss the model to explain the Xenon-1T result. In section  an analysis of the
dark matter relic density is given.
A discussion of the inelastic dark matter-electron scattering is given in section .
Event detection rates in the Xenon-1T detector are discussed in section .
Constraints on the model and a fit to the Xenon-1T data is given in section .
Our conclusions are given in section . Several details of the calculation
are given in the Appendix.
